Erysipelas has a worldwide distribution and is of economic importance throughout Europe, Asia, Australia and North and South America. Pigs 3 months through 3 years of age are most susceptible to erysipelas. Affected pigs often have swollen and stiff joints and they do not gain weight efficiently. Also, their carcasses are often trimmed or condemned by inspectors at packing houses.
About 10 years ago it was shown that the conventional practice of making E. rhusiopathiae vaccines from whole killed cultures was unnecessary. A bacterium-free filtrate worked just as well in protecting both pigs and mice against virulent challenge. Subsequent published research by Japanese and U.S. scientists has confirmed this finding and shown that E. rhusiopathiae releases into the culture medium an antigen that is a universal immunogen in that it immunizes pigs against all E. rhusiopathiae strains (Sawada and Takahashi, 1987, Am. J. Vet. Res. 48:239–242; Groschup et al., 1991, Epidemiol. Infect. 107:637–649). Groschup et al. showed that a 64 to 66 kDa protein in the culture protected mice against challenge with virulent E. rhusiopathiae. Having shown that such a protein also protects pigs, the USDA provides vaccine makers with a monoclonal antibody (mAb) to this protein for use in assaying the protein.
Although an effective vaccine to prevent erysipelas in pigs is very desirable, none of the many traditional erysipelas vaccines provides acceptable protection for weaned pigs. The problem is lack of duration of immunity. The pig industry requires a vaccine that, given at weaning, will protect pigs against this lethal, devastating disease until slaughter age, i.e., approximately 6 months. The USDA has specified this requirement as a standard for the licensing of new vaccines.